Alternating-current motor.



D. M. BLISS.

ALTERNATING CURRENT MOTOR.

APPMQATION FILED MAE. 13. 1911.

.-gatented Jan. 26,1915.

UNTTED sTATEs PATENT oEEIcE.

303m x. 32.185,92 WEST ORANGE, NEW J-EasEY, NssIeNon :po rnonn's A.EmsoN,v mcononunn, or WEST ORANGE, NEW maaar, a coaroan'rloN or NEWJERSEY.

aanname-CURRENT MOTOR Application lled latch 13, 1911. Y SerialNo.'614,277. F?

Y To zZ-l 'whom it may concern:

` Be it known that I,- DoNALD M. BLISS, a subject of the' Kin of GreatBritain, and a resident of'West range, in the county of Essex andStatevof New Jersey, have in-' vented certain new anduseful'Improvements in Alternating-Current'Motors, of which thefollowing is a specification.

My linvention relates generally to alternating current motors, and moreparticularly to motors adapted to be operated syn' chronously from asingle phase alternating current circuit. I

The object of my invention is to produce a simple, eicient,self-starting synchronous motor, adapted to operate on a single phasecircuit.

My improved motor is particularly adapted for driving devices, such asmechanical rectifiers, for commutating alternating current waves intounidirectional currents, and for -any other purposes in which exactsynchronism with an alternating current is deL sired.

In the operation of mechanical rectiiers` it fis important to maintainperfect synchronism, and also to be able to. adjust the angular positionof the rotor ofthe motor, an

the rectifying devices connected thereto, Y

with respect to th'e phase of the alternating current which is beingrectified in order that the rectifying device -may operate withoutsparking.

A further object of my invention is to provide a motor in which thisadjustment maybe easily and effectively made.

My improved motor comprises a field structure or stator, provided with asuitable exciting winding, and arotor consisting of a core'of magneticmaterial provided with a commutated winding and a short circuited systemof conductors, the core having axially extending slots lwhich divide itinto sections or polar projections, equal in number tothe poles of thefield structure. tated winding is connected to the segments A .of acommutator, .and suitable brushes are provided for the commutator.

The brushes are preferably short circuited` but my invention is notlimited to this arrangement of connections.

My invention consists further in the details- 'of construction andcombinations 'of parts, hereinafter more particularly de scribed andclaimed.` .I

Speciatilon of Letters Patent.

The commu- Patnited J aan. 26, 1915.

In some aspects my present invention is an 1mprovement on that describedin my copending application Seriall No. 614,276 filed on even dateherewith.

In the accompanying drawings which forni a part of this specification,and in which like reference characters refer to like parts in theseveral views:-Fig'ure l is a showing a modified arrangement of connec.

tions. i Referring to the drawings, the stator, or held frame, of thealternating current motor 1s shown at l. The field frame may be of anyof the forms wellknown in the vart and A1s preferably laminated. It mayor may not have projecting poles, and is provided ywith asuitableWinding 2, which may be either distributed or concentric. In thedrawings, I have illustrated .a four pole motor, with the windings ontwo of the poles omitted, but obviously my invention is applicable tomotors of any number of poles. In Fig. of the drawings, the fieldwinding 2 is shown cornected to the alternating current mains The rotor,or armature of the motor is mounted to rotate within the influence ofthe iield produced by the winding 2, and comprises a core 5' of magneticmaterial which is preferably cylindrical-in form and laminated. The coreis provided with three sets of axially extending openings at 'or nearits periphery,and preferably uniformly distributed. The setv of openings6 consists of deep slots. which extend across the face of the rotor andmay be parallel with the axis of the rotor, or slightly spiraled so asto aid the motor in starting. The slots 6 are uni formlyndistributed anddivide the face of the rotor into as many lsections asthere are Vwinding-aroundthe r'otor'and contain a commutated slots nearly closed, ut maybe of any lform suitable to contain the commutated winding. Thecommutated winding' 9 may be any v' form of closed coil armature'winding and' vis connected 1n: the usual manner t'o the seg ments ofthe commutatorlO. The -commutions shown' in Fig?) in whichfthe brushesare shortcir'cuited, but a series-.'c'omiection.-

' may bev employed, that is, the field winding and thecommutated windingmay be connected in series through the brushes 'across the line, as is.illustrated in Fig.'f4. The- 'third set of openings 8 c arry'the activeconductor's of a squirrel 'cage system off con lnetio-'material havingtwo sets of axially `extending, -openings', near the periphery ductorsVor windings, whlch consist preferably of bars 13 of copper or otherconduct- -ing materiaL-whichare united'at their ends l by disks, orrings, 14 of copper, or other lconducting material. The openings 8 areshown as tunnels containing the bars 13, but obviously any suitable formof opening may be employed-e1 The openings 8 with their bars 13 arelocated'between the openings 7 containing'the commutated winding,'except l, at thosepoints-where the ldeep slots 6 occur.

At thesepoints the bars ofthe squirrel cage .system of "conductors areomitteL The squirrel *cage u winding has `preferably an even'number-ofbars in each section or polar projection of the rotor. `The brushes 11may 'bemounted' on an adjustable'arm -or ring, 15, sothat they may beshifted around the i commutator, 'thus varying the line ofcommutation.`1 Themode of operation of my improved motor is in brief as follows: Whenan alterhating electromotive H force is'impresed on the Afield winding,the motor starts as a re-I pulsion motor, and when itA has reached aspeed near synchronis'm, `it'drops into `exact synchronisln and ismaintained at synchro- "nousspeed by the combined inductive edect "1 -ofthe' iield on the'sectionsor polarvprojections of the' rotor andthesquirrel cage winding. The angular position ofthe rotor, with vrespect 'to the impressed alternating electromot1ve force,'may beshifted forward or backwardby shifting the brushes forward lor backward,and thus changing the linlof commutation. My improved motor isfthe'revfore particularly adapted for the 'operation of a rectifying commutator.Inasmuch as 'the commutated winding -is-of high -resi'stance, thestarting current isrelativelysmall.l

- arrangement of winaingsaescribea-the com re-thermen, a ist@ be noted,that .in the mutated winding is surrounded by the squir- 9.' Thevopeningsf'? 'are shown' as ing, substantially; as described.-

rel cage system of short circuited conductors. The eilect of this.arrangement-LI is toslppress sparking at the commutator, even. when'the brushes are displaced considerably from the line ofnormal'connnutation. .v Having describedmy invention, what I claim asnew and desire' to secureby Letters Patentais as follows 1. An armaturecomprising a core of mag-l netic material, having polar projections, andprovided with a shortoircuited system of- -conductors and acommutatedjwinding, and

a commutator 'andshort' circui-ted brushes for the commutated winding,substantiallyas described. v 2. An armature comprising a core ofmagnetic material having polar projections and provided with.ashortcircuited system of conductors and a comutated winding, andl aconductors and a distributed commutated winding, substantially asdescribed.

3. An armature comprising a core of magthereof, l`andsubstantially-,equidistant therefrom, a closed circuited winding in oneof .es i

said sets Ofopeniii'gs and a commutated winding in the other of `saidsets, the 'said core having also. an additionalset of axially extendingopenings,-whereby polar projec tions are formed, substantiallyas.described.y

4. In an alternating current motor, a core of magnetic material havinguniformly distributed axially extending. openings near the y peripherythereof, a uniformly distributed commutated winding in some of said onings, and a short circuited system of con t' ucvtors in' some, butnotall, of the remaining openings, substantiallyasA described.

to the 'poles of the stator, `the said core being provided withauniformly distributed commutated winding and a shortcircuited windandrotor members of magnetic material,

,of said members being provided with two secondary or induced windings,one being a commutated winding uniformly distributed,

and the other bein a'short circuitedv winding having its active..conductors arranged tween any two adJacent groups being greater than thes between any two adjacent Aactive vcon uctorsJv of agroup,substantially as. described.-

7. Asynchronous having a stator 'y and a rotor, one of said membershaving a active conductors arranged in spaced apart groups equal innumber to the number of poles produced by the primary or inducedwinding, the'space between any two adjacent groups bein greater than thespace between any two a jacent active conductors of the group, and acommutatorand adjustable short-circuited brushes for the commutatedtween any two a winding, .substantially as described.

8. A synchronous motor, having a stator anda rotor, one of said membershaving a primary or inducing winding, and the other of said membershaving two secondary or induced windings, onebeing a commutated windinguniformly distributed, and the other a short circuited winding havingits active conductors arranged in spaced-apart groups e ual in number tothe number of poles pro uced by the primaryor inducing winding, thespace between any two adjacent groupsbeing greater than the spacebejacent active conductors of a grou and means for determining andshiftin t e axis of commutation of the commutate winding, substantiallyas described.

9. A n armature comprising a core of magnetic material having polarprojections and provided with a short-circuited system of conductors anda commutated winding, the

active conductors of said system and Winding being located in the facesof the polar projections, substantially as described.

10'. In an alternating current motor, the combination withY a fieldframe or stator adapted to be energized by alternating current, of arotor comprising acore of magnetic material having polar projections andprovided with a short-circulted system of conductors and a distributedcommutated winding, and means for adjusting the angular position of therotor with respect'to the impressed alternating electromotive force,substantinally as described. l. Y f This specification signed andwitnessed this 10th day of March 1911.

, DONALD BLSS.

Witnesses: FREDERICK BACHMANN,

ANNA R. KLEHM.

